Compact Orthomode Transducers Using Digital Polarization Synthesis

TL;DR

This paper introduces a new class of compact digital orthomode transducers that use digital calibration and multiple probes to achieve high polarization isolation, reduced size, and stable performance across temperature variations.

Contribution

The paper presents a novel digital calibration approach for orthomode transducers, enabling high polarization isolation with minimized size and volume.

Findings

Achieved over 50 dB polarization isolation

Maintained performance over a 10°C temperature range

Demonstrated effectiveness with prototypes having three and four probes

Abstract

In this paper we present a novel class of compact orthomode transducers which use digital calibration to synthesize the desired polarization vectors while maintaining high isolation and minimizing mass and volume. These digital orthomode transducers consist of an arbitrary number of planar probes in a circular waveguide, each of which is connected to an independent receiver chain designed for stability of complex gain. The outputs of each receiver chain are then digitized and combined numerically with calibrated, complex coefficients. Measurements on two prototype digital orthomode transducers, one with three probes and one with four, show better than 50 dB polarization isolation over a 10 C temperature range with a single calibration.